Fig. 1.

The effect of palmitic acid (PA) or stearic acid (SA) on LPS-stimulated IL-6 secretion from macrophages. Bars with different symbols in the bar graphs have significantly different values. A: RAW 264.7 cells were treated with different concentrations (0.1–1 ng/ml) of LPS in the absence or presence of 100 μM PA for 24 h. + and *P < 0.01; ++ and **P < 0.01. B: human monocyte-derived macrophages were treated with 0.1 or 0.5 ng/ml LPS in the absence or presence of 100 μM PA for 24 h. After treatment, IL-6 in culture medium was quantified using ELISA. + and *P < 0.01; ++ and **P < 0.01. C: RAW 264.7 cells were treated with or without 1 ng/ml LPS in the absence or presence of different concentrations of PA (50–200 μM) for 24 h. After the treatment, IL-6 in culture medium was quantified using ELISA. # and *P < 0.01; + and *P < 0.05. D: RAW 264.7 cells were treated with 1 ng/ml LPS in the absence or presence of 100 or 200 μM SA for 24 h. After treatment, IL-6 in culture medium was quantified using ELISA. + and *P < 0.01; # and *P < 0.01; # and +P < 0.01. E: the effect of bovine serum albumin (BSA)-unconjugated PA (free PA) and BSA-conjugated PA (PA/BSA) on IL-6 secretion induced by LPS. RAW 264.7 cells were treated with 1 ng/ml LPS in the absence or presence of 100 μM free or BSA-conjugated PA for 24 h. After treatment, IL-6 in in culture medium was quantified using ELISA. + and *P < 0.01; ++ and +P < 0.01. F: PA does not augment Toll-like receptor (TLR)2 signaling. RAW 264.7 cells were treated with 1 ng/ml fibroblast-stimulating ligand-1 (FSL-1) (TLR2/6 ligand), pam2CSK4 (TLR2/6 ligand), or pam3CSK4 (TLR2/1 ligand) in the absence or presence of 100 μM PA for 24 h. After treatment, IL-6 in culture medium was quantified using ELISA. The presented data (means ± SD) were from 1 of 3 experiments with similar results.